One of the areas where incremental progress is easiest to miss is global health. It's hard even to say the word "progress" in the face of continued suffering, but this year has brought some significant achievements.

Not 15 years ago, an HIV diagnosis was medically considered a death sentence, and policymakers worried whether the world could contain the spread of AIDS. In that context, today's news is surprising: AIDS infections have dropped 50 percent or more in 25 countries, compared with a decade ago, reports the Joint United Nations Program on HIV/AIDS (UNAIDS).

"For many years, we've been talking about the millions of people dying from AIDS, which is still the case in many countries, but for the first time we see the light at the end of the tunnel," says Christoph Benn, director of external relations and partnerships at The Global Fund to Fight AIDS, Tuberculosis and Malaria. "Treatment prices have come down, and you're now finding drugs not just in hospitals, but in rural clinics."

UNAIDS reports that the number of children newly infected with HIV is down by more than a quarter in the past two years. "This progress in reducing new infections among children is actually quite dramatic," says Peter Ghys, chief of Data for Action at UNAIDS. "We're seeing this in a large number of countries."

One place that might be lagging? The United States. A November report by the Centers for Disease Control and Prevention said that young people ages 13 to 24 make up fully a quarter of new HIV infections each year; and 60 percent of them don't know they are infected, making it impossible to medically treat them.

Antiretroviral therapy is credited with reducing the pace of HIV-related deaths and limiting the transmission of the virus. The UN Millennium Development Program put universal access on the global agenda. Though it failed to meet the objective by its 2010 deadline (now revised to 2015), this year for the first time the majority of people eligible for HIV treatment in low- and middle-income countries receive ART. Dr. Benn singles out Rwanda as an example of stunning progress: More than 90 percent of eligible Rwandans were receiving ART by the end of October.

"This is fantastic ... historical. That is beyond our expectations from a couple of years ago," Benn says.

Kazakhstan is the site of another moment of global public health progress this year. In March, it was certified malaria-free by the World Health Organization, joining only four other malaria-endemic countries with that designation.

Nigeria heads the pack of 17 countries poised to eliminate malaria. Their antimalaria agenda includes a $50 million bed-net program, underwritten by The Global Fund, which hopes the country will offer two bed nets per household.

The Republic of the Congo, meanwhile, has made massive strides in combating maternal mortality. The number of women dying in childbirth dropped 60 percent between 2010 and 2011, from 740 deaths per 100,000 live births to 300 deaths.

David Lawson, who heads the UN Population Fund's Congo Republic office, says a government strategy and increases in the health budget have been factors in the change. Starting in March, Caesarean sections were offered free of charge, reducing deaths from delivery complications.

More than 80 percent of Congolese women deliver babies in health centers, an unusually high rate in sub-Saharan Africa, which Mr. Lawson attributes to the Congo Republic's high degree of urbanization. But he did caution, in an e-mail interview, against too much optimism: "While such a significant drop is spectacular and certainly unusual in Africa [the maternal mortality rate nevertheless] remain[s] very high for a middle-income country where women deliver babies in health centers."